PCV valve
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
PCV valve Tried to do a search and it came up with 248 threads but not what I was looking for. I noticed the PCV valve on my 2003 5.3 LM4 is just a tiny hole and connected to the valve cover with a 3/8" hose. Up front there is just a 3/8" hose. Took the intake manifold off today and it was very oily on the inside. Seems the system is sucking up oil in the name of clean air. What would happen if I made a plug to go into the front 3/8" hole with a small hole thru it the same size as the hole in the PCV valve? Will this work? Anyone try it? Thanks.
GM switched to a PCV in the valley cover with the LS6 and beyond for just the reason you are worried about. It has an internal baffle and PCV valve built in. While far from perfect it does a much better job of keeping oil out than the valve cover vents.
Catch can with either system is always good insurance. Oil mist in the intake lowers the effective octane of the fuel and can lead to detonation.
Catch can with either system is always good insurance. Oil mist in the intake lowers the effective octane of the fuel and can lead to detonation.
Teching In
Joined: Aug 2015
Posts: 4
Likes: 0
From: Jenkins, KY
What I did was vent the oil cap. The crankcase can breathe, and the PCV lines don't pull enough vacuum to suck up quite as much oil. I'm running a C5 intake manifold on an LM7 5.3, and had to use the LS1 type PCV system...except that the DBW throttle bodyI'm using had no provision for the vent line...thus the vented oil cap.
I used a little breather filter from Spectre...
The rubber boot on the bottom of the filter was a tad larger than .750, so I drilled a .750 hole through the oil cap, put some RTV on the boot, and twisted it into the cap.
Finished cap looks good, and matches the Spectre air filter I used on my swap.
I used a little breather filter from Spectre...
The rubber boot on the bottom of the filter was a tad larger than .750, so I drilled a .750 hole through the oil cap, put some RTV on the boot, and twisted it into the cap.
Finished cap looks good, and matches the Spectre air filter I used on my swap.
